Google kills Right Hand Side Ads: what does this mean for marketers and users?

There’s been a great deal of speculation on what this means for businesses, advertisers and users alike, with many postulating that the top-of-the-page paid search is going to become even more cutthroat (and expensive), organic listings will be pushed even further off the first SERP (Google will start to show four ads at the top instead of three for “highly commercial” search terms) and that Product Listing Ads will gradually take over the SERP (PLAs are still allowed on the right-hand side).